It is known that, in industrial electric plants having a considerable number of inductive loads, the power factor may easily fall below 70%, for example. However, since many power companies impose a surcharge when the power factor is below a preset value (for example, 90%), it would be advantageous to have a corrective system whereby the power factor may be regulated within acceptable limits thereby avoiding this surcharge.
There are two well known methods of regulating the power factor. In a first system, capacitive loads are connected to the transmission lines. In a second system, capacitive loads are simulated by means of a synchronous motor having a winding over-excited with continuous current. These two systems are frequently used, the second being especially used in cases where the number of reactive KVA is of importance.